This invention relates to the testing of switched digital service communications lines, and more particularly, this invention relates to a system and method of testing an IDSL communications line.
The rise of the internet has created a demand for higher speed internet access from residents, using the standard copper wire pairs in end-user-owned loops, such as in campus environments and high-rise buildings. The existing copper wire local loops have been designed for voice telephone using twisted pair wiring. The bandwidth in many of these copper wire local loops often are limited by bridge taps and wire gauge changes. To provide high-speed internet access across the copper wire, it was necessary to provide an economical way to increase the bandwidth along the existing twisted pair copper wires.
Digital subscriber line (DSL) technology provides the technology that improves the bandwidth of existing communication lines along the standard copper local loop. The type of DSL service that can be used depends on the distance of a premises from the central office, the type of bridged circuits, and the use of digital loop carriers (DLC). Some telephone companies installed digital loop carrier frames around existing wire centers, particularly in high growth areas to provide newer lines. Any concentrators are digital, and include fiber optic technology. They were designed before the advent of digital subscriber line technology and do not support this technology.
A digital loop carrier, on the other hand, supports integrated services digital network (ISDN) technology, using a high-quality switched digital service to the premises. In a basic rate interface (BRI), two bearer (B) channels of 64 Kbps each, and a 16 Kbps signaling (D) channel are operative to provide up to 128 kilobits per second of data along the existing copper wire local loop to provide digital voice and data channels.
Problems often develop with providing DSL not only with a digital loop carrier, but also along communication lines that are spaced a great distance from the central office. Therefore, a new service well known as ISDN DSL (IDSL) operates at speeds of about 128 Kbps. Although these speeds are less than speeds offered by most other digital subscriber line technologies, IDSL provides for access over the twisted pair copper wires used for single-line voice telephone service. IDSL acts as a dedicated service as a data only service, lacking an analog voice line that other digital subscriber loop technologies offer, such as asymmetric digital subscriber loop technologies (ADSL). An IDSL line can pull traffic that otherwise would tie up a voice switch and drop it onto a frame relay network to handle virtual circuits.
The IDSL circuits use IDSN transmission coding, bundling together both ISDN channels and voice all on one circuit. Because of this, different types of tests common for XDSL technologies, such as a multi-meter test and wideband loop performance test, cannot be operative past the first digital loop controller in a typical IDSL circuit. It is necessary to confirm circuit operation downstream of the digital loop carrier to provide critical information to speed up deployment and maintenance of IDSL communication lines. There are some known communication and test sets, such as disclosed in U.S. Pat. No. 6,185,191 to Dipperstein; U.S. Pat. No. 6,215,854 to Walance; and U.S. Pat. No. 6,163,594 to Kennedy et al. Although these units are operative for testing ISDN transmission coding, they do not provide for adequate ISDL testing.
It is therefore an object of the present invention to provide a method and system of testing an IDSL communications line to identify the configuration of the IDSL communications line.
It is yet another object of the present invention to provide a method and system of testing an IDSL communications line that overcomes the drawbacks as noted above.
The present invention is advantageous and provides a method and system of testing an IDSL communications line. Transmission elements are queried sequentially within the IDSL communications line. A predetermined period of time is waited after querying a transmission element to receive a correct response. If a correct response is received, the next transmission element is queried for its existence. The configuration of the IDSL communications line is identified based on the received responses.
In yet another aspect of the present invention, the transmission elements are queried by using an auxiliary IDSL channel, such as an embedded operations channel. The network terminator can be detected, which is considered as the last element in the communications line. The step of waiting for a correct response can include the step of waiting for a correct embedded operations channel message. If a correct response is not received within a predetermined period of time, then the last network element is considered as identified. A correct response can be received after a predetermined period of time, and the next sequential transmission element is queried for its existence. The step of querying the next sequential transmission element can occur only when the number does not exceed six transmission elements. The step of periodically querying the last transmission element located within the IDSL communications line can determine any changes within the configuration of the IDSL communications line. The transmission elements can comprise repeaters, while the communications line comprises a twisted pair copper wire as part of the local loop.
A test set for testing an IDSL communications line is also disclosed and includes an interface circuit for interfacing with an IDSL communications line. A processor is connected to the interface circuit and transmits a query command along the IDSL communications line and queries transmission elements sequentially along the communications line and identifies the configuration of the IDSL communications line based on the received responses. The processor and interface circuit can be operative for transmitting the query command along an auxiliary IDSL channel, such as an embedded operations channel. The transmission elements can comprise signal repeaters.